1. Field of the Invention
The instant disclosure relates to an automatically-switchable network extension apparatus and a switching method therefor, more particular to a network extension apparatus performing an automatic switching according to the operational mode of the other network extension apparatus.
2. Description of Related Art
FIG. 1 shows a conventional architecture of VDSL system. The system has a CPE (Customers Premises Equipment) end X and a CO (Center Office) end Y. The CPE end X is such as a home subscriber of a telecommunication service, and the CO end Y is preferably a telecommunication company. In which, the connection is made by two different network devices respectively installed at the CPE (X) and CO (Y) ends. For example, the CPE-end transmitting device 11 and the CO-end transmitting device 12 are connected via a copper wire 101. This wire 101 is simultaneously carrying voice signal and data.
FIG. 1 shows an implementation of a VDSL system. The CPE-end transmitting device 11 operates as a signal splitter, which is used to split the data and voice signal over the copper wire 101. In practice, the splitter is functioned to filter the high and low-frequency signals with the data and voice. The CPE-end transmitting device 11 particularly filters out the voice signals and transmits the signals to its linked home telephone 13. On the other hand, the voice signals can be transmitted to the CO end via the CPE-end transmitting device 11 from the telephone 13.
Furthermore in the present example, the CPE-end transmitting device 11 transmits the data to an ADSL Transceiver Unit Remote (ATU-R) 14. The data then undergoes an analog-to-digital conversion and demodulation, and serves the user-end computer 15 via network. User may use the computer 15 to transmit the data to the CPE-end transmitting device 11 via the ADSL Transceiver Unit Remote 14. The data is then transmitted to CO-end device. The splitting means performed by the CPE-end transmitting device 11 carries and receives both voice signal and data by carrier wave, the voice signal and data are split up into different applications.
Center office employs the CO-end transmitting device 12 to link with the CPE-end transmitting device 11. This device 12 is also functioned to perform the splitting in order to split the CPE end voice and data. The voice signal is transmitted over PSTN (public switched telephone network) 18 via a voice PBX 16. On the other hand, the split data is transmitted to a DSLAM (DSL access multiplexer) 17. This DSLAM 17 effectively integrates the IP network and an ATM network 19. At last, the data is transmitted to the network service provider (ISP) 191 or an enterprise 193.
Similarly, the splitting function performed by the CPE-end transmitting device 11 or the CO-end transmitting device 12 also combines the voice and data, or splits them after receiving.
In the VDSL system, the CPE end and CO end respectively employs different transmitters (11, 12) with different splitting schemes. The CPE end device and the CO end device are connected via the copper wire 101. It is noted that the VDSL system preferably requires installing the CO-end transmitting device as a master, and the CPE-end transmitting device as a slave.